It is known that certain quinolone compounds possess antibacterial activities. For example, D. Chu, U.S. Pat. No. 4,607,032, issued Aug. 19, 1986, which is incorporated herein by reference, has disclosed 1-substituted amino-2-fluoro-4-oxo-4H-quino[2,3,4-i,j][1,4]benzoxazine-5-carboxylic acid derivatives which possess antibacterial activity. Closely related quinobenzothiazine and quinobenzoxazine derivatives having antibacterial activity have also been disclosed by Chu in U.S. Pat. Nos. 4,528,285, issued Jul. 9, 1985; 4,529,725, issued Jul. 16, 1985; and 4,542,133, issued Sept. 17, 1985. However, these and other related novel derivatives have not been known heretofore to be antineoplastic agents.